# Electric Field Strength

Electric field strength is the force per unit positive charge. It's like how gravity pulls objects together, electric force happens because of an electric field. But, electric fields are way stronger than gravitational fields. This is because the Coulomb constant is larger than the gravitational constant. Any charged particle makes an electric field around itself. If two charged particles are close, they will interact.

Generally, electric field lines point towards a negative and away from a positive charge.

## Electric field strength: Interaction between electric fields

Electric fields differ from gravitational fields in that they can have a positive or negative direction. On the other hand, gravitational fields only have a positive direction. This makes it easier to calculate the direction of an electric field at any time in free space.

The more densely packed the field lines, the stronger the field. Field lines are also useful if many charges are interacting with one another. Figure 3 is an example of an electric dipole, as the charges are opposite.

## Electric field strength formula

To measure an electric field generated by a point charge, we use electric field strength. Electric field strength is the force that a +1 C charge (called a test charge) experiences when it's in an electric field. We measure electric field strength in Newtons/Coulombs, where E is the electric field strength, F is the force in Newtons, and Q is the charge in Coulombs.

The strength of the electric field depends on where the charge is located. If the charge is in an area where the field lines are dense, the force experienced will be stronger. It's important to note that the equation given above is only valid for linear fields.

We assume that all charges are point charges, meaning that all the charge is concentrated at the center and has a radial field.

In a radial electric field, the electric field strength can be represented as:

Here: E is the electric field strength measured in Newtons per Coulomb. Kc is the Coulomb constant with a value of 8.99⋅109.Q is the point charge in Coulombs. r is the distance from the point charge in metres. Electric field strength follows an inverse square law: if the distance from Q increases, the strength of the field decreases.

## How can we use an electric field?

Yes, if two charged plates are applied a voltage across them, with one of them having a positive and the other a negative charge, then in between the plates, an electric field will be induced that is parallel and uniformly distributed. The electric field strength equation is E = V/d, where E is the electric field strength (V/m or N/C), V is the potential difference in Volts, and d is the distance between the plates in metres. This equation states that the electric field strength is directly proportional to the potential difference applied across the plates, and inversely proportional to the distance between the plates.

The electric field strength acts perpendicular to the plates, and when a test charge is put in a uniform electric field, it will experience a force towards the negative end of the terminal or plate. As the electric field is uniform, the electric field strength will be the same regardless of where inside the field the test charge is put.

### Electric field strength: A test charge entering a uniform field with a velocity

If a charged particle enters a uniform electric field with some initial velocity, it will experience a force that depends on the direction of the field and the charge of the particle. If the charge enters the field at a right angle to the field lines, it will experience a constant force that acts parallel to the field lines inside the plates.

In the case of a positively charged particle entering a uniform electric field at a right angle, it will flow in the same direction as the field lines. This causes the positive charge to accelerate downward in a curved parabolic path, as shown in Figure 7. The exact trajectory of the charged particle will depend on various factors such as the strength of the electric field, the mass and charge of the particle, and the initial velocity.

It's also worth noting that if the charged particle enters the electric field at an angle other than 90 degrees, the force acting on it will have a component perpendicular to the field lines. This will cause the charged particle to move in a curved path that is not necessarily parabolic. The exact path will depend on the angle of entry and other factors mentioned above.

If the charge is negative, the direction will be in the opposite direction to the field lines.

Yes, those are some key takeaways about electric field strength, including:

• Electric field strength is the force exerted by a +1 C charge (test charge) when it is placed in an electric field.
• Any charged particle creates an electric field around its vicinity.
• Point charges behave as if all the charge is concentrated at their center, and they have a radial electric field.
• A uniform electric field is generated between two oppositely charged plates, and the direction of the electric field lines is from the positive plate to the negative one.
• In a uniform electric field, the electric field strength is the same throughout the field.
• If a charge enters a uniform electric field with some initial velocity, it will bend, with the direction depending on whether the charge is positive or negative.

## Electric Field Strength

Is electric field strength a vector?

Yes, electric field strength is a vector quantity.

What is electric field strength?

Electric field strength is a force experienced by a positive 1 C charge placed in an electric field.

How do we calculate electric field strength between two charges?

We can calculate the electric field strength with the formula E = kq/r2 via both charges at any point where a test charge is placed in between them.

Can electric field strength be negative?

Electric field strength cannot be negative as it is just a force acting on a 1 C charge.

How do we find the electric field strength inside a capacitor?

The electric field strength inside a capacitor can be found by dividing the voltage applied to the plates by the distance between them.